Technical Abstract:
Salmonella enterica is an important food-borne pathogen and an excellent model system for the study of genomics, virulence and pathogenesis. . There are over 2,400 Salmonella serotypes each of which differs in their ability to cause disease in humans and animals, persist within the host, and survive in the environment. DNA microarray technology has enabled us to determine the genome organization and gene content that leads to variations in Salmonella serotypes. This has been accomplished by comparative genomic hybridization (CGH), a method which has revealed that each serotype of Salmonella contains a core of approximately 4000 genes; in addition to that, there are approximately 400-600 genes that are serotype specific. Some of these genes are shared between closely related serotypes; however, others are shared with very distantly related serotypes or with other bacteria via horizontal gene exchange. Genomic targets from this work were identified based on their differential distribution among common serovars. A multiplex PCR incorporating a fluorescently labeled primer and analyzed in an automated sequencer was used to detect these unique genes and is capable of correctly identifying the top 50 Salmonella serotypes in a rapid high-throughput assay. Antimicrobial resistance in Salmonella is also a major concern. Analysis of mutlidrug resistant (MDR) Salmonella is hampered by difficulty determining which resistance genes are responsible for observed pheontypes in isolates. To address this, a microarray for the detection of antibiotic resistance genes was developed. This microarray is able to detect hundreds of resistance genes, and can be used to analyze a variety of diverse bacteria including important pathogenic and commensal bacteria such as: Campylobacter, E. coli, Enterococcus, Listeria, MRSA, Salmonella and A. baumannii.